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Bridge conditions in Lake County, South Dakota

79 inventoried bridges · 4 rated poor · 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

4 of the 79 bridges the federal inventory lists in Lake County are rated poor; the rest split 35 good and 40 fair.

4 of the 79 bridges in Lake County, South Dakota, are rated in poor condition (5.1%) in the 2025 National Bridge Inventory, as of August 20, 2026.
35 bridges (44.3%) are rated good and 40 (50.6%) fair.
The median Lake County bridge was built in 1985.
The busiest poor-rated bridge is 461 Ave over Ck (built 1950), carrying about 580 vehicles a day.

Good 44.3% · Fair 50.6% · Poor 5.1% of 79 bridges

Bridges rated poor

Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.

Bridge	Built	Vehicles/day	Condition
461 Ave over Ck	1950	580	Poor
449 Ave over Ck	1930	290	Poor
231 St over East Fork Vermillion Rv	1930	55	Poor
464 Ave over Battle Ck	1930	15	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
SD034 over Silver Ck	2000	8,695	Fair
414 NE Second Str over Madison Ck	1959	7,576	Fair
SD034 W over Park Ck	1977	3,631	Fair
SD034 E over Park Ck	1977	3,631	Fair
500 N Egan Ave over Madison Ck	1993	3,190	Fair
610 S. Egan Avenue over Silver Ck	1979	2,915	Fair
SD019 over Park Ck	2014	2,881	Good
US081 over East Fork Vermillion Rv	1983	1,811	Fair
US081 over Ck	1997	1,811	Good
US081 over Ck	1997	1,811	Good

Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.

All of South Dakota: South Dakota bridge conditions by county · every download on the data page.

Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.